Narcotics are the mainstay of treatment for pain control after surgery and trauma. Evidence from in vitro studies of human immune function and from animal studies suggests that narcotic use may impair function of the immune system, an undesirable effect. Impaired immunity can result in increased susceptibility to infection after surgical or non-surgical trauma and enhanced tumor growth after cancer surgery. These concerns have practical implications for two reasons; first, alternatives to narcotic analgesia may cause less immune suppression and, second, techniques to restore narcotic-induced immunosuppression may be possible. This study will evaluate in vivo effects of the narcotic, morphine, on human immune function and explore the possibility of restoring narcotic-induced immune suppression. To study the effects of morphine on human immune function, we plan to admit twenty normal volunteers to hospital for a 24-hour, intravenous infusion of morphine. We will evaluate antibody dependent cell cytoxicity (important in control of bacterial infection and antibody-directed cancer therapy), natural killer cell cytotoxicity (important in control of viral infection and cancer) and gamma interferon production (to evaluate the mechanism of narcotic-induced immune suppression). We will study these measures of immune competence before, during and after exposure of volunteers to morphine. Morphine blood levels will correlate morphine exposure with changes in immune function. With the study completed, we will have; 1) a foundation for defining the effect of narcotics on human immune function, 2) information to guide clinical decisions regarding use of narcotic analgesics or alternatives to narcotic analgesia, 3) preliminary data to guide future studies evaluating the effect of different analgesic techniques on postoperative immune function and, 4) preliminary data to guide future studies evaluating techniques for restoration of narcotic-induced immune suppression.